A control method for realizing full-range soft switching of three-phase inverter four-quadrant operation

Abstract

The present invention is a control method for realizing full-range soft switching of four-quadrant operation of a three-phase inverter, including step 1, building a converter system, the converter system includes a three-phase inverter topology, a digital controller, a sampling circuit and a drive circuit; Step 2, decompose the load phase current to obtain d-axis and q-axis components for current closed-loop control; use DPWM modulation to obtain modulated waves; Step 3, perform load phase current, load phase voltage and DC bus voltage Sampling, the digital controller updates the carrier cycle in real time; the driving circuit drives the corresponding switching devices to realize soft switching within the full range of all switching devices. By analyzing the critical switching frequency curves of switching devices to achieve soft switching under different power factors, the minimum critical switching frequency curve is used as the switching frequency curve of all switching devices to achieve soft switching, which solves the problem of three-phase inverters operating under different power factors. The problem of large switching losses has a higher switching frequency.

Description

Technical field [0001] The present invention belongs to the field of power electronics technology non-isolated high-frequency power conversion direction, specifically relates to a control method to achieve a three-phase inverter four-quadrant operation of a full range of soft switching. Background [0002] Three-phase inverters are widely used in various types of industrial equipment and civil devices, such as photovoltaic systems, stationary reactive power generators or AC asynchronous motors, etc., in these applications mostly need to consume reactive power, so the three-phase inverter is required to have the ability to generate or absorb reactive power, that is, the three-phase inverter can work under non-unit power factor conditions. In the traditional three-phase inverter, because half of the switching devices are in the hard switching state when they are working, the switching loss of the switching devices is very large, so the switching frequency of the switching devices i...

AI Technical Summary

Problems solved by technology

Since the zero-crossing moment of the inductor current on the three-phase inverter side is not synchronous, the switching device corresponding to the zero-crossing phase first and the switching device corresponding to the zero-crossing phase are controlled to be turned off at the same time. Although frequency synchronization can be achieved under this control method , but will cause the current to appear discontinuous

In the working condition of non-unity power factor, this document only analyzes the power factor from leading 0.8 to lagging 0.8, and the soft switching of switching devices under the full power factor range needs to be realized

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